Today's modem speeds allow
dialup access at rates up to 56 Kbps
. However, due to the poor quality of twisted -pair line
between many homes and ISPs, many users get an effective rate significantly less than 56
Kbps. Whereas dialup modems require conversion of the end system's digital data into
analogue form for transmission,
so-called narrowband ISDN
technology(Integrated Services Digital Network) allows for all -digital transmission of data from a home end system over ISDN 'telephone' lines to a phone company central office. Although ISDN was originally conceived as away to carry digital data from one end
of the phone system to another, it is also an important network access technology that provides higher speed access (for example, 128 Kbps) from the home into a data network such as the Internet.
In this case, ISDN can simply bethought of as abetter modem'.
Share with your friends: 
